New Delhi : India, Central Asia, Middle East and Central Sahel are among areas expected to be among the earliest to face above-average surface temperature increases and intensifying water scarcity in the next 30 years. These areas could also experience migration due to water woes, a new report has indicated.

Global water use has increased by a factor of six over the past century, twice the rate of population growth, and its scarcity is now a looming human challenge due to a host of factors ranging from climate change and pollution to lack of capacity and infrastructure, said the FAO.

FAO Director-General José Graziano da Silva said that two-thirds of the global population lives under conditions of severe water scarcity for at least part of the year.

That has a particularly heavy impact on people who depend on agriculture and some, especially the poorest, may see no alternative to migrate and in search of better livelihoods. "But migration should be a choice, and not the only remaining option," Graziano da Silva stressed.

In a new research report - 'Water stress and human migration' - done with Global Water Partnership and US-based Oregon State University, on the nexus between water and migration, the FAO has reviewed more than 100 detailed studies, analyzing their results in terms of demographics, surface temperatures and rainfall histories.

"Agricultural adaptation strategies affect many people's need to migrate and should be explicitly factored into climate change and other policies. Analyzing water scarcity trends and engaging in preparedness are particularly valuable, allowing time to intervene to mitigate pressure for forced migration," said FAO Land and Water Division Director Eduardo Mansur.

"Enabling proactive adaptation is a more effective and sustainable strategy than offering a reactive humanitarian response in the face of large-scale distress", Mansur said.

A key finding of the report is that more information on the dynamics of the migration-water linkage is needed for India, Central Asia, the Middle East and the Central Sahel. South and Southeast Asia are also relatively understudied given their long coastlines and low-lying river deltas, and while water scarcity in South America and North Asia is less intense, evidence about migration pressures there is scant.

According to the report, water stress typically refers to situations in which demand is not met due to a combination of access issues and decline in the availability and/or the quality of water.

It tends to increase as a result of higher temperatures, growing demand from the agricultural, energy and industrial sectors, and may reflect greater rainfall extremes or vulnerability to flooding as well as more frequent drought-like conditions. Inadequate infrastructure can exacerbate shortfalls in water quantity and quality.

While some studies demonstrate a correlation between water stress and higher outmigration, the causal interaction is still not clearly understood, according to the report.

"It is essential to make sure the interaction between water scarcity and migration does not become one of mutual aggravation," said FAO's Deputy Director of Land and Water Olcay Unver.

Water is one of the world’s gravest risks, according to the Global Risks Report published earlier this week at the World Economic Forum in Davos. And the situation is actually worse than it might seem at first glance.